Taking Differential Measurements with the BNC-2090A

Updated Apr 24, 2023

Reported In

Hardware

  • BNC-2090A

Issue Details

I am using a BNC-2090A to route signals to a DAQ device that only has differential input channels. How do I set up the BNC-2090A to ensure that my signals are properly read on the DAQ device?

I am measuring signals using a differential probe that terminates in a BNC cable. As far as I know this probe is measuring a signal voltage value, not a pair of values. Do I need to configure the BNC-2090A to be in 'SE' (single ended) mode in this case or in 'DIFF' (differential) mode?

Solution

In order to properly measure your signal set your BNC-2090A to be in the 'DIFF' configuration. BNC cables inherently transmit a differential pair of signals, so even though your probe terminates in a single BNC cable, that cable is transmitting two differential signals.

As shown in Figure 2-2 below, taken from the BNC-2090A's User Manual, by connecting a single BNC cable to AI 0 in the 'DIFF' configuration, the BNC-2090A will break out that BNC cable's differential pair into 2 signals and send one signal to AI 0 on the DAQ device and the other to AI 8 of the DAQ device. You are only connecting 1 BNC cable to the BNC-2090A but it will send 2 distinct signals to the DAQ device, complying with the differential input requirement.
 

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